Web Conference with Dr. Janet Rossant

Web Conference with Dr. Janet Rossant - 00:00 Thank you for taking the time to speak with us, so obviously we'd like to ask you some questions about your work and your research, but can you tell us about yourself and your research, how you got into stem cells in the first place? - 00:16 Okay, so I've been interested in early development for a very long time, sort of all my research career. I started as a graduate student at the University of Cambridge with Richard Gardner who was one of the first people who developed techniques to inject cells into blastocysts to make chimeras, and so I was always interested in how an egg develops into a complex organism, and over the years I've worked on the cell lineage in the early embryo. We've then been able to move in and identify some of the genes and pathways that specifies cell fate in the early embryo, and of course along the way, stem cells come into the picture because it's from the early mammalian embryo, the blastocysts, that you can derive embryonic stem cells, and it's really the work that I and my colleagues did early on in the embryo showing that there was a subset of cells that were pluripotent that gave people the idea that maybe you could capture that pluripotency and derive permanent cell lines from those cells and grow them in cultures. So we've worked on mouse embryonic stem cells, but we also have been able to show that we can derive stem cells from the other two types of the blastocysts, the trophoblast and the primitive endoderm, so in the mouse you can have three stem cell lines from the blastocysts, each of which replicates the properties of those lineages in vivo. So we've been able to sort of use those stem cell lines and the embryo itself to really look at the genetic pathways that specify cell fate and of course control pluripotency, so our link to stem cells really comes through our interest in embryonic development, and it's only in the last few years that we started to move from the mouse into the human, recognizing that as human embryonic stem cells were developed and then more recently human iPS cells, that if we really truly want to take those cells and derive therapeutically useful cell types from them, then we, the developmental biologists, better get their act in there and show people how it's done and having spent all this time saying that developmental biology is what we need to understand, to drive cell fate, then we better start Web Conference with Dr. Janet Rossant working with the human cells, see if the same rules apply, and start seeing whether we can apply developmental principles to take human embryonic stem cells forward into useful cell types for therapy perhaps in the long run, but in the more short run, cell types that we can study human biology and disease in the Petri dish, so in a capsule, that's the sort of link between my early interest in the embryo and the current interest of, you know, a lot of people around the world in stem cell research. - Thank you. That's great. - 03:04 Does anyone have any follow ups? Just to give a little context for a lab that is working on human embryonic stem cells, how big is your lab? - 03:15 My lab? My lab, I have currently five post docs and four graduate students and a couple of technicians, so it's medium sized, a medium sized outfit I would say. - Okay, thanks. - So our first questions is from Beck here. - 03:34 Hi, so I just had more of a broad question about the use of stem cells in general, so what are the major differences when you're comparing the study in the use of mouse stem cells and human stem cells? Is it more expensive to work with human stem cells? Are there different techniques or legal loopholes you have to jump through to work with human stem cells, especially in Canada as opposed to the U.S.? - 03:58 Yeah, a lot of questions under that heading. The sort of practical issues of working with mouse versus human embryonic stem cells is that human stem cells are a lot harder to work with just physically in terms of their tissue culture requirements. They grow very slowly. They're very difficult to dissociate and passage in culture, whereas mouse embryonic stem cells, although when they were first derived they were quite hard to work with, over the years we've kind of learned how to work Web Conference with Dr. Janet Rossant with them and know better how to handle them than we do with the human cells, so I think that's part of the difference is it's just early days in people really understanding how to work with the human embryonic stem cells, but certainly they are much more finicky. Cost wise? Well, it's quite expensive every time you do any kind of major scale tissue culture, not so much just the plasticware, but it's usually the additives you have to grow the cells in. Whether you use fetal calf serum, which is what we usually use for mouse cells, that gets pretty expensive, but the human cells, people really want to grow them in more defined conditions that don't have xenogeneic extracts in them, so the growth factors that you require just to grow the cells in are pretty expensive so that the tissue culture costs are quite high. There's no question. The regulatory issues, I think you asked that, and somebody else asked that later on, and what's the situation in Canada versus the States? So the situation in Canada is that we have legislation that passed four years ago now, around reproductive technologies in general, and amongst the various clauses of that are clauses that regulate the use of human embryos in research, and there's lots of detail there, but the bottom line is that it is possible in Canada to work with human embryos that are in excess from in vitro fertilization programs. Otherwise it would not be used for reproductive purposes, provided that you have a strong justification. You have ethics approval. You have informed consent, et cetera, et cetera, so it's possible to still, in Canada, to derive new embryonic stem cell lines and work with existing embryonic stem cell lines, provided that they're derived under the guidelines of the act. Interestingly the act is supposed to set up a regulatory body to which you should apply for a license to do your work. 2005 was when the act was passed. The body is in place. It's passed one regulation. It has yet to even work out a process for delivering your license, so eventually everybody is grandfathered, but there is a stem cell oversight committee that the Canadian Institutes for Health Research, which is the Canadian equivalent of the NIH, has, so if you want to do a human embryonic stem cell research in Canada, there is the legislation, which doesn't really work, but there are also guidelines from the funding agency, so you have to send your protocols to them for approval, so it takes time. Yeah, yeah, there is a regulatory step that Web Conference with Dr. Janet Rossant slows down the research, but on the whole, once you get through that regulatory step, it's less onerous than it has been at any rate in the U.S. - Do we have any follow up questions now? - 07:20 Sure, do you foresee at any time in the next, oh, 10 or 20 years the ability, you said it was more difficult to work with mouse cells when you were first working with them. Do you foresee it becoming easier therefore to work with human cells in the coming years? - 07:39 Yeah, I think so. I think so. Don't know exactly where that's gonna go, but one of the issues which comes up, one of the other questions, that not only are the human ES cells difficult, more difficult to grow and work with than the mouse ES cells, we think they're not really the same cells, that their properties are not equivalent to the same developmental stage, and part of the reason why human embryonic stem cells are really hard to work with is that they really are quite hard to dissociate. They don't like growing as single cells. They like to be in little groups of cells and, you know, you start dissociating, you just lose the cells. They die, and that's not particularly the case with mouse embryonic stem cells, but it is the case for these mouse epiblast stem cells that are derived from slightly later stages of development, so that's one of the properties that, again, suggest that epi stem cells are more like human ES cells, so if it were possible to derive from the human cells that really do resemble exactly the same properties and stage of development as the mouse ES cells, they might be as easy to grow as a mouse ES cell. However, to date nobody has managed to do that, and it's not really still clear whether that's going to be possible or not, but never say never. What you learn very much in this kind of research area is that there are always surprises around the corner, and if you had told me two years ago that you could take an adult skin cell and turn it into an embryonic stem cell by throwing four genes at it, I might not have said you were crazy, but I would have perhaps been somewhat skeptical of your ideas.

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